In the manufacture of conventional filling carriers for shuttleless looms, a carrier member is attached to a flat tape by a brazing operation. Experience has shown that a considerable number of tapes fail from fatigue in the area immediately behind the point where the carrier is attached. It is believed that the reason for such failure is because the tape has a reduced hardness in this area resulting from the brazing operation, and because the section size and stiffness drastically increases due to the attachment of the carrier at such point. The increase in stiffness causes most of the flexing in the tape to occur just behind the point where the carrier is attached in the aforesaid area of low tape hardness.
The tape is manufactured generally from an austempered AISI 1064 steel, and a "bubble" is formed in an annealed area for the purpose of strengthening such area. The carrier is then brazed with silver solder to the tape, so that tails of the carrier straddle the "bubble." Where the tape has an initial hardness in the range of 73-75.5 Rockwell A, after brazing, the tape hardness adjacent the carrier is generally in the range of Rockwell A 65, but has been measured to be as low as Rockwell A 53.
While a logical approach to improve the tape hardness in the brazed area might seem to be a quenching operation where tape is quenched with water just after brazing, such cannot be done. The reason that the quenching operation cannot be done is because the brazing alloy will crack.
Therefore, in accordance with the present invention, there has been developed a two-step approach to the solution of this problem. First of all, it was realized that there was a need to reduce the abrupt section change and rigidity at the end of the carrier, so as to reduce the flexing stresses. This was accomplished by tapering the tails of the existing carrier design to a contour having an angle beginning at the upper end that was initially steep, then flairing the taper to gradually converge with the tape surface. This results in a gradually decreasing cross-section with a smooth transition into the tape.
Secondly, to further reduce the flexing stresses at the end of the carrier, the flexing point was moved from the area immediately behind the carrier to an area behind the bubble by placing a tin alloy in the hollow chamber formed by the bubble. The tin alloy serves to stiffen the bubble, and cause flexing to take place further rearwardly in the tape.
The results of this two-step approach are surprising. Whereas, neither step alone provides significant improvement as far as fatigue life is concerned, when both steps are effected, the tape life is increased at least four to six times the normal life expectancy.
It is therefore an object of the present invention to provide an improved and strengthened filling carrier for shuttleless looms that enjoys a longer useful life.
It is another object of the present invention to provide an improved filling carrier of the type described in which the strength of the carrier is increased by reducing the flexing stresses in the weakened area of the tape which has been previously subjected to a brazing operation.